mesh faces permanently highlighted?
Crease indicators

Pink colored edges in Blender is used to show edges that have a crease greater than the default value (which is -1). As written in the manual's page, crease is:


  ...used to define the sharpness of edges in subdivision surface meshes.


You can set the crease of the selected edges by pressing the Shift+E shortcut and enter a numeric value. Here's a few examples of possible values:


-1 - edge doesn't have any sharpness (no purple color)
+0 - edge have an average sharpness (dark purple color)
+1 - edge is sharp (bright purple color)


You can also control the visibility setting of this overlay (an many other such as seams or sharp edges...) in the Mesh Display panel of the Properties bar.